Hi, i am trying to inform the customer that the store will be temporary closed during a specific time. so i use the traditional alert code

    alert("blah blah blah");


but the problem is when i go to the website, this pops up and the background is gray or white, depends on the browser. the webpage shows only after the user click OK. how can you make the box pops up after the webpage is loaded? i tried putting the alert code in the body  tag, but still when it pops up, it still covers the whole webpage content with gray background.

how can i make it looks like this? it shows the box and the website content in the back.